Lessons Ascertained from the U.S. Shale Revolution: Abating Fugitive CH4 Releases from Unconventional Shale Gas Extraction

Krokus, Alexander1,2

1Ethical Environmental Policy Consortium, Portland, United States, 2Mark O. Hatfield School of Government, Portland State University, Portland, United States

The δ13C signal of CH4 associated with unconventional shale gas has been observed as lighter than the signal produced by conventional gas (Golding et al., 2013; Hao and Zou 2013; Turner et al. 2017; Botner et al. 2018; Howarth 2019).  Originating in 2009, the isotopic composition of CH4 in our atmosphere has become depleted and lighter, containing less 13C and more negative δ13C (Schaefer et al. 2016; Nisbet et al. 2016), a physical trait exhibited by gas trapped in unconventional tight formations possessing low permeability, that has not been exposed to oxidation.

The considerable upsurge in CH4 fluxes experienced globally since 2005 has been attributed to the commercialization of shale gas in North America (90% of it occurring in U.S. and 10% in Canada), rather than by biogenic sources (Hausmann et al. 2016; Turner et al. 2016; Rice et al. 2016; Howarth 2019).  NOAA observed an increase of 3.27ppm of CH4 globally from 2000-2006 (0.46 ppm per year), and an increase of 85.76 ppm during 2007-2018, averaging 7.15 ppm per year (NOAA 2020).  During 2006, the U.S. extracted 3 bcf of unconventional shale gas per day.  In December 2018 that amount rose to 65 bcf per day (US EIA 2019a).  Moderate estimates of increases of CH4 leakage ensuing the U.S. shale gas revolution during 2008-2014 are predicted to be 9.4 Tg per year (Alvarez et al. 2018; Howarth 2019).  CH4 possesses a GWP of 84-87 x CO2 over 20 years (US EPA 2020), and diminishing fugitive CH4 leakage from shale gas operations is an advantageous method for restricting extreme weather events (Shindell et al. 2012).

Currie et al. 2017 has demonstrated that infants born within 1km of an active HF well site will experience a 25% increase in the probability of low birth weight, and additional detrimental consequences arise when infant births occur within 3km.  Increases in childhood hematologic cancer incidences (Elliott et al. 2017; McKenzie et al. 2017), and infants born with congenital heart defects have also been observed in close proximity to HF activities (McKenzie et al. 2019).  Apergis et al. 2019 performed an empirical analysis of births occurring in all of OK’s 76 counties, beginning with the inception of the U.S. shale revolution in 2006, up until 2017.  Substantial birth complications (low birth weight and premature births) were only observed when infants were born within 5km of an UOG well site, with more severe effects transpiring within 1km.  Their regression analysis (births from 1996-2005) did not display any statistical impact on infant health prior to the inception of the U.S. shale revolution in 2006. 

Mandating the implementation of quantitative methods for CH4 leak detection when an active HF well site is within 5km of a human population, would diminish adverse effects associated with infant mortality, increase worker safety, and provide energy security by capturing CH4.  Optical gas imaging can be achieved from a far distance, ensuring the safety of the operator, and can be utilized in natural gas processing plants, power generation plants, and also offshore platforms.


Alexander served in the Oregon State Legislature as an Environmental & Economic Policy Aide for Senator Lew Frederick.  He is now a Senior Policy Advisor for the Ethical Environmental Policy Consortium, and has been successfully collaborating with federal legislators in the U.S. House of Representatives to enact bipartisan energy policy. 

CO2 reduction and fermentation producing in situ CH4 in the majority of sampled GAB aquifers and alluvium overlying a coal seam gas field

Pearce, Julie1,2, Golding, Sue2, Baublys, Kim2, Hofmann, Harald2, Herbert, St.John3, Hayes, Phil1

1University Of Queensland, Brisbane, Australia, 2Arrow Energy Pty Ltd, Brisbane, Australia

Understanding the origin and source of gas in aquifers with multiple users is of increasing importance.  The Walloons coal seams are a major coal seam gas (CSG) resource in Queensland, where various shallower and deeper aquifers are part of the Great Artesian Basin (GAB).  Dissolved gases and waters were sampled from water bores in the Gubberamunda, Mooga, Orallo, Hutton, Precipice and Springbok Sandstones, the Condamine Alluvium, Walloons bores, and also CSG wells.  The majority of δ13C and δ2H of CH4 and CO2 sampled from shallow aquifer bores indicated in situ primary microbial CO2 reduction, with three water bores in the Gubberamunda, Mooga, and Walloons plotting in the fermentation pathway region.  CSG wells and a gassy Springbok bore however plotted in the secondary microbial region, typical of biogenic CSG.  The majority of the Condamine Alluvium bores sampled had very low CH4 concentrations, with δ13C-CO2 in the range -17 to -21 VPDB‰, and δ13C-DIC +2.2 to -13 ‰.  The range of δ13C-DIC from CSG wells (+16 to +19 ‰) was typical of methanogenesis.  Stable isotopes of water encompassed a wide range, with Alluvium samples and one Walloons water bore more enriched.  A gassy Springbok bore, CSG wells, and deeper bores had depleted values consistent with recharge during colder climates or greater impact from microbial-water-rock reactions.  Strontium isotopes of aquifer waters were mainly more radiogenic and distinct from CSG waters indicating dis-connectivity in the majority of cases.  Results so far suggested that CH4 was formed in situ (rather than leakage) in the majority of our samples, however in a few cases sources could not be determined.  Analysis of a subset of samples for δ14C, 36Cl, 34S, and CH4 clumped isotopes are also in progress.


Dr Julie Pearce is a geochemist with international experience in the UK, Japan, and Australia on interdisciplinary projects.  She is currently working on field monitoring techniques for measurement of methane and understanding its sources through isotopic techniques, in addition to CO2 storage, and geochemical processes in gas and oil shale. 

Petroleum source rocks of Western Australia – an overview

Ghori, Khwaja Ameed Ur Rehman1

1Department Of Mines, Industry Regulation And Safety, Perth, Australia

Western Australia is the largest State in Australia and contains several Precambrian and Phanerozoic basins. The stratigraphic and geographic extents of these basins are very large and all contain several potential source rocks. The age of these source rocks ranges from Neoproterozoic to Mesozoic. Many of these basins are underexplored with potential for undiscovered petroleum resources. 

Some of these source rocks have sourced significant discovered volumes of petroleum resources accumulated within sand, carbonate and shale reservoirs of Western Australia. Currently, the Canning, Northern Carnarvon and Perth Basins have commercial production, whereas there is no producing fields in the Amadeus, Bight, Bonaparte, Browse and Officer Basins within Western Australian jurisdiction.

The Amadeus, Bonaparte and Browse Basins have at least one genetically related oil family; the offshore Carnarvon Basin has four, the Canning Basin has three, and the Perth Basin has four. These oil families have been identified from chemometric and statistical analysis of a large regional multivariate dataset.

These oil families are interpreted to be sourced from:

  • Amadeus Basin — the Tonian Gillen, Loves Creek and Wallara formations, the Cryogenian Areyonga and Aralka formations, the Ediacaran Pertatataka Formation, the Cambrian Pertacorta Group, the Ordovician Horn Valley Siltstone within Ordovician Larrapinta Group and Devonian Pertnjara Group
  • Bonaparte Basin — Devonian Ningbing Group and Bonaparte Formation and Carboniferous Milligans Formation
  • Browse Basin — Jurassic Plover and Vulcan formations, Cretaceous Echuca Shoals Formation
  • Canning Basin — Carboniferous Laurel, Devonian Gogo, and Ordovician Goldwyer formations
  • Northern Carnarvon Basin — Jurassic Dingo Claystone and Triassic Locker Shale
  • Southern Carnarvon Basin — Devonian Gneudna Formation, Lower Permian Wooramel and Byro groups
  • Officer Basin — Neoproterozoic Brown, Hussar, Kanpa, and Steptoe formations
  • Perth Basin — Permian Carynginia and Irwin Coal Measure,  Jurassic Cattamarra Coal Measures, Triassic Kockatea Shale

KEYWORDS: Amadeus Basin, Bonaparte Basin, Browse Basin, Canning Basin, Carnarvon Basin, Officer Basin, Perth Basin, petroleum source rock, petroleum systems, Western Australia


Ameed Ghori is an experienced petroleum geologist/geochemist. Specializing in managing TEAM based integrated petroleum and geothermal system studies. He has up-to-date knowledge developed through various short-courses, conference-presentations on Australian, Ugandan, Libyan, and Pakistani basins that are published in national and international journals. Plus various company confidential reports.

Unconventional Gas and resources

Garnett, Prof. Andrew1

1Centre for Natural Gas, The University of Queensland, Brisbane, Australia

Primary energy demand is set to grow significantly over the next few decades. There is an increasing realisation that natural gas has several critical, complex and, to some extent, counter-intuitive roles in pursuing a “less than 2 deg C” scenario. With reference to the IEA’s Sustainable Development Scenario, natural gas will need to remain abundant and affordable and socially and environmentally acceptable in order to fulfil these roles. However, the proportion of gas that is traded as LNG looks set to grow, at least for a while, and importantly, the proportion of gas that comes from unconventional sources is also forecast to grow. This has significant implications, for example, for the confidence needed in sub-surface prediction of resources and their flow behaviour, as well as for the technologies and technical costs by which they are developed. The challenges of the future are harder than those of the past. There will be significant, new trials which only geoscientists and petroleum engineers can resolve. This presentation will highlight the main technical challenge areas and the contribution that earth science professionals will have to make within the complex and wicked energy trilemma.


Andrew leads the Centre for Natural Gas at The University of Queensland, which provides leading technical and social science research for the sector. Andrew has over 25 years international experience  in conventional and unconventional hydrocarbon exploration, appraisal and development projects, and carbon, capture and storage.

The Distribution and Origin of Hydrogen Sulphide Gas in the Triassic Montney; unconventional Play, British Columbia and Alberta, Canada

Chalmers, Gareth1, Bustin, Amanda2 and Bustin, Marc2

1 University of the Sunshine Coast, Sippy Downs, Australia, 2 University of British Columbia, Vancouver, Canada

The distribution and origin of hydrogen sulphide (H2S) within the Triassic Montney Formation of the western Canadian sedimentary basin (WCSB) were investigated in British Columbia and Alberta, Canada. Hydrogen sulphide is a toxic gas that can be co-produced with hydrocarbons and impacts well economics and the environment. Even small amounts of H2S can impact hydrocarbon operations by depositing ‘elemental sulphur’ within pipelines and compressors as observed in Australia and overseas.

This study has mapped the H2S concentration in the Upper, Middle and Lower sections of the Montney Formation as operators are drilling multi-directional well pads within three zones of a 200 m reservoir. The Montney Formation has tested or produced H2S gas at concentrations between 0.001% and 22%. The stratigraphic and lateral variation in the H2S concentration can be inexplicable.

Sulphur available to generate H2S includes sulphide oxidation, decomposition of well-completions surfactants, bacterial sulphide reduction, kerogen cracking or fluid migration of sulphate ions from sulphur-rich evaporites. The isotopic ratios of sulphur and oxygen will depend on the source and the formation pathway of the H2S gas and these ratios can be used to help model H2S gas generation. Samples were collected from the Triassic Charlie Lake, Doig, Montney formations and the Devonian Nisku, Elk Point and Muskeg formations within areas of sour wells. Organic matter, sulphate and sulphide minerals were isolated using chemical and physical mineral separation techniques. These samples were analysed for sulphur and oxygen isotopes at the Ján Veizer Stable Isotope Laboratory, University of Ottawa (Ontario, Canada). Sulphur and oxygen isotopic ratios from sulphate minerals within the Montney Formation and the Charlie Lake Formation have a range between 9.0 to 18.0 ‰ V-CDT and -5.0 to 19.0 ‰ V-SMOW, respectively. These isotopic ratios differ from the sulphur and oxygen isotopic ratios from sulphate minerals sampled from Devonian rock sources which vary between 18.0 to 30.0 ‰ V-CDT and 12.0 to 30 ‰ V-SMOW, respectively. The sulphur isotopic ratio measured from H2S gas of producing Montney Formation wells varies between 9.3 and 20.9 ‰ V-CDT.

Preliminary results from isotopic analyses suggest that the sulphur that generated H2S in the Montney Formation is from Triassic sulphates or a mixture of Triassic and Devonian sources and not solely from Devonian rocks as first expected. It is postulated that the sulphate ions have migrated through localised fractures into the Montney Formation and then the sulphate is used to generate H2S. Another possibility is the H2S gas formed in the Charlie Lake Formation and/or Devonian rocks and then migrated into the Montney Formation. Textural relationships between the reservoir rock and the sulphate minerals is currently being examined which will provide key data for creating a H2S generation model for the Montney Formation.


Gareth Chalmers has used a multidisciplinary approach to investigate coal seam gas and shale reservoirs since 2002 at University of British Columbia, Canada. He also worked at Shell to develop the Duvernay shale play. Gareth now lectures at the University of the Sunshine Coast and is researching Australian gas reservoirs.

A very unconventional hydrocarbon play: The Mesoproterozoic Velkerri Formation of Northern Australia

Collins, Alan S.1, Cox, Grant M.1, Jarrett, Amber J.M.2, Blades, Morgan L.1, Shannon, April, V.1, Yang, Bo.1, Farkas, Juraj1, Hall, P. Tony1, O’Hara, Brendan3, Close, David3, Baruch, Elizabeth, T.4, Altmann, Carl4, Evans, David5, Bruce, Alex5

1Tectonics and Earth Systems Group, The University Of Adelaide, Adelaide, Australia, 2MinEx CRC, , , 3Geoscience Australia, Canberra, Australia, 4Santos Limited, Adelaide, Australia, 5Origin Energy Ltd, Brisbane, Australia, 6Empire Energy, Sydney, Australia

The ca. 1.5–1.3 Ga Roper Group of the greater McArthur Basin is a component of one of the most extensive Precambrian hydrocarbon‐bearing basins preserved in the geological record, recently assessed as containing 429 million barrels of oil and eight trillion cubic feet of gas (in place). It was deposited in an intra‐cratonic sea, referred to here as the McArthur‐Yanliao Gulf.

The Velkerri Formation forms the major deep‐water facies of the Roper Group. Trace metal redox proxies from this formation indicate that it was deposited in stratified waters, in which a shallow oxic layer overlay suboxic to anoxic waters. These deep waters became episodically euxinic during periods of high organic carbon export. The Velkerri Formation has organic carbon contents that reach ~10 wt%. Variations in organic carbon isotopes are consistent with organic carbon enrichment being associated with increases in primary productivity and export, rather than flooding surfaces or variations in mineralogy.

Although deposition of the Velkerri Formation in an intracontinental setting has been well established, recent global reconstructions show a broader mid to low latitude gulf, with deposition of the Velkerri Formation being coeval with the widespread deposition of organic rich rocks across northern Australia and North China. The deposition of these organic‐rich rocks may have been accompanied by significant oxygenation associated with such widespread organic carbon burial during the Mesoproterozoic.


Alan Collins is a tectonic geologist with wide ranging interests in basin analysis and plate tectonic controls on the development of the earth system

About the GSA

The Geological Society of Australia was established as a non-profit organisation in 1952 to promote, advance and support Earth sciences in Australia.

As a broadly based professional society that aims to represent all Earth Science disciplines, the GSA attracts a wide diversity of members working in a similarly broad range of industries.